Apparatus for hydraulic control of the valves of an internal combustion engine or motor compressor



3,119,592 RAULIC CONTROL OF THE VALVES w m E mo H M3 C O S C A R a R N F WM F u mF OF AN INTERNAL COMBUSTION ENGINE APPARATUS FOR HYD Jan. 28, 1964 in Ven F145 zhd i' Fran L2 bo H'ttornfy United States Patent Ofifice 3,119,592 Patented Jan. 2a, 19

igagNuovo Pignone S.p.A., Florence, Italy, a company of Filed Jan. 30, 1961, fler. No. 35,633 Claims priority, application Italy Feb. 10, H50 1 Claim. (U. 251-57) The present device relates to an improvement in the hydraulic control of the main valve of an internal-combustion engine or motor-compressor and in particular to an improvement in the hydraulic tappets associated with an advance and retard device.

The applications of hydraulic control to the distribution system of internal combustion engines are well known as are also the advantages thereof namely: the elimination of play in the control mechanism, a considerable reduction in the weight of moving parts thus enabling rapidity in control movements to be achieved, the reduction of bulky linkages in the transmission system to a minimum, etc.

In such applications, however, there is no provision for being able to vary the timing of the valves. It is, however, often very important to be able to vary this timing in order to give the engine better performance when running at different speeds from normal and also for other reasons.

The object of the present invention is to improve the application of hydraulic control to the main valves (exhaust, air intake, fuel intake valves) of engines and motorcompressors by making it possible to vary the start of the opening of the valves, that is to regulate at will the tim ing thereof.

This object is achieved according to the invention by varying the pressure of the fluid feeding the valve control system. Hydraulic control is elfected by means of two hydraulic cylinders herein referred to as the control cylinder and the operating cylinder, which are interconnected by a system containing oil or some other fluid.

On account of the compressibility of the oil contained in the system, the shifting of the operating cylinders plunger is not synchronous with the shifting of the control cylinders plunger.

Since this compressibility is a function of the jump in pressure caused by the oil itself, the retarding of the valve opening control is influenced by the pressure existing in the feed system.

By varying the feed pressure of the system it is thus possible to vary the timing of the motor, that is the instant of opening not only of the intake valve but also of the exhaust valve and of any other valves there may be. This makes it possible to achieve optimum timing for every number of engine revolutions.

One embodiment of the invention is shown schematically in the accompanying drawing.

The device consists of a plunger 1 which, under the action of cam 2, moves inside the guide member 3 thereby compressing and shifting the fluid column which lies above it in the conduit system 15. This fluid column, which may be composed of oil or other suitable fluid, extends from guide member 3 to guide member 4 which is mounted on the valve, and acts on the plunger 5 which is disposed within guide member 4. This plunger, being impelled by the fluid, causes the valve to open. The latter will return to the closed position as soon as the rotation of the eccentric contour of cam 2 allows plunger 1 to return to its rest position, and the fluid column, actuated this time by valve spring 6, is enabled to move in the opposite direction to that in which it was caused to move during the opening stroke.

In its rest position, plunger 1 uncovers a hole bored in guide member 3 so that, with the hole open, fluid is enabled to pass from the supply tank 8 through checkvalve 7 into the inside of guide member 3; in this manner the column is replenished with any fluid it might have lost, and maintained, in its rest position, at a pressure equal to that existing in the supply tank 8.

During the work stroke of plunger 1, the feed system is doubly closed by both the check-valve 7 and the closing up of the hole bored in guide member 3; plunger 1 closes up this hole immediately on starting its upward stroke.

At this point it should be observed that in the work stroke plunger 5 and hence the valve will begin to move as soon as the pressure in the fluid column has reached such a level that it exerts on plunger 5 a force equal to the resistance of the spring 6. Since the compressibility, however slight, of the fluid prevents the pressure from reaching this level at the same instant as plunger 1 begins to move, a portion of the stroke of said plunger will be idle as regards the actuation of the valve. The idle portion of the stroke of plunger 1 is equivalent to the difference in the volume of the fluid column which is produced when passing from the pressure at rest to the pressure suflicient to cause the movement of plunger 5 and the valve. It is manifest that this difference in volume will be proportional to the ditference between the rest and control pressures, which means that there exists the possibility of regulating the length of the idle stroke of plunger 1 and hence the retardation in the control of the valve, by appropriately regulating the pressure at rest of the fluid column, which can be effected by regulating the pressure in the supply tank 8. To this end there is connected to the supply tank 8 a conduit 9 wherethrough a pump it) pumps a certain flow of fluid under pressure, whilst there is a further conduit 12 wherethrough a regulated flow of fluid returns to tank 14 from which the pump 10 draws.

The amount of fluid flowing can be regulated by means of a valve 13 which permits the pressure in the supply tank 8 to be regulated, that is to say by means of a reliefvalve with a variable setting which causes the pressure in the supply tank 8 to be equal to that for which the reliefvalve has been set to open. 16 denotes a relief-valve for venting air from the line 15.

I claim:

Apparatus for controlling the movement to and from its seat of a reciprocable valve that has a head at one end to engage said seat and a stem extending from said head, said apparatus comprising (a) a spring constantly urging said valve toward its seat and for holding said valve seated, and

(b) means for moving said valve off its seat comprising (0) a conduit,

(d) a first plunger reciprocably mounted in one end of said conduit,

(e) a second plunger reciprocably mounted in the other end of said conduit and contacting the end of said valve stem,

(f) a compressible liquid filling said conduit and transmitting motion between said plungers,

(g) a rotary cam operatively connected to said first plunger to move said first plunger inwardly of said conduit during part of a revolution of said cam, to cause the column of liquid in said conduit to move said second plunger outwardly of said conduit to lift the valve off its seat against the resistance of said spring, said spring operating to seat said valve, to move said second plunger inwardly, and through operation of the column of liquid moving said first plunger outwardly during another part of a revolution of said cam, and i (h) a second conduit positioned to be connected normally to the first-named conduit through a port in the first-named conduit,

(i) said port being located so as to be closed by said first plunger when said first plunger is moved by said cam inwardly of said first-named conduit a predetermined distance,

(j) a check-valve for closing the connection between the two conduits,

(k) spring means for continuously urging said checkvalve to closed position but permitting said valve to be opened when a predetermined pressure exists in said second conduit,

(1) a tank connected to said second conduit for supplying said compressible liquid under said predetermined pressure to said second conduit to open said check-valve against the resistance of the last-named spring whereby the pressure in said first conduit may be controlled and the amount of movement of said first plunger required for opening said reciprocable valve may be controlled,

(m) a pump connected to said tank to pump liquid into said tank, and

(n) an adjustable relief valve connected to said tank, said relief valve being adjustable to set the maximum pressure of the liquid in said tank and said conduits.

References Cited in the file of this patent UNITED STATES PATENTS 1,810,465 Da Costa June 16, 1931 2,072,437 Wurtele Mar. 2, 1937 2,126,885 Heintz Aug. 16, 1938 

